Surface-active compounds for use as coating aids for film-forming coating compositions

ABSTRACT

COATING COMPOSITIONS INCLUDING A HYDROPHILIC COLLOID AND AT LEAST ONE COMPOUND OF THE FORMULA:   R-(CH2)N-(OCH2CH2)MOSO3M   WHEREIN: M STANDS FOR 0 IN WHICH CASE N IS 1 OR M STANDS FOR 1 TO 30 IN WHICH CASE N IS 0 OR 1, M STANDS FOR HYDROGEN, AN ALKALI METAL ATOM, AMMONIUM OR ORGANIC AMMONIUM, AND R STANDS FOR A BRANCHED-CHAIN ALIPHATIC GROUP OF 8 TO 20 CARBON ATOMS, WHICH HAS AT LEAST 2 POINTS OF BRANCHING ARE DISCRIBED. THE COATING COMPOSITIONS ARE PARTICULARLY USEFUL IN THE FORMATION OF PHOTOGRAPHIC SILVER HALIDE MATERIALS AND THE LAYERS COATED THEREFROM DO NOT EXHIBIT HYDROPHOBIC AREAS LEADING TO REPELLENCY SPOTS OR COMETS.

United States Patent US. C]. 9667 14 Claims ABSTRACT OF THE DISCLOSURE Coating compositions including a hydrophilic colloid and at least one compound of the formula:

m stands for 0 in which case n is 1 or m stands for 1 to 30 in which case n is 0 or 1,

M stands for hydrogen, an alkali metal atom, ammonium or organic ammonium, and

R stands for a branched-chain aliphatic group of 8 to 20 carbon atoms, which has at least 2 points of branching are described. The coating compositions are particularly useful in the formation of photographic silver halide materials and the layers coated therefrom do not exhibit hydrophobic areas leading to repellency spots or comets.

This invention relates to surface active compounds suitable for use as coating aids for film-forming coating compositions comprising a hydrophilic colloid, and to hydrophilic colloid compositions comprising said coating aids.

In the application of film-forming coating compositions comprising a hydrophilic colloid to surfaces, particularly in the photographic industry, it is desirable to apply such coating compositions uniformly and at good production speeds. In many cases it is even desirable to apply such coatings over other previous layers, which are either wet or dry.

It is necessary, in the photographic industry, that colloid compositions ready for coating are entirely hydrophilic to obtain a uniform layer therewith comprising no hydrophobic inclusions that may lead to repellency spots or comets in the said layer. Moreover, the entire surface of a layer formed from such colloid compositions should be hydrophilic so that it can be rewet readily either by the processing solutions if said layer is the top layer of a photographic material to be processed, or by the coating composition, that will be applied to said layer for forming a next layer. Indeed, during processing, air-bubbles are more easily carried along by a hydrophobic surface than by a hydrophilic surface, which air-bubbles will manifest themselves as small undeveloped areas in the processed material; moreover, when the material comprises hydrophobic inclusions so that its surface is not entirely hydrophilic but shows hydrophobic areas, water will not uniformly wet the said surface in that it is repelled on the hydrophobic, areas and form drops thereon. After processing such materials cannot be dried uniformly. They show a poor retouchability when it is desired to retouch such like materials.

In the case wherein the layer formed from the said colloid composition is overcoated with a following layer, the maximum speed of the moving layer to be overcoated, at which no repellency occurs can be increased, when and to the extent that the surface to be overcoated is more hydrophilic; local hydrophobic areas at the surface of the "Ice layer to be overcoated can give rise to the formation of so-called repellency spots or comets in the said next layer.

Thus, in order to eliminate all these possible coating defects such as air bubbles, repellency spots, or comets the use of coating aids has been widely adopted.

Saponin is conventionally used as coating aid for coating compositions comprising hydrophilic colloids. Though this product excells by its favorable anticomet action, it may vary markedly from batch to batch and is much more expensive than synthetic coating aids.

A number of synthetic surface active agents have been proposed for use as coating aids to facilitate the coating of compositions comprising hydrophilic colloids more particularly gelatin layers. Most of these coating aids do improve some properties of the layer. However, they also adversely affect other desired properties. For instance, hydrophilic colloid layers comprising coating aids, which pervent the formation of comets in the said layers, may have an inadequate rewettability, which causes difficulties in the processing of photographic elements or it may be diffiicult to overcoat such layers when in wet state which is quite undesirable especially in simultaneous multilayer appilcations. In order to overcome these disadvantages it has been proposed to use mixtures of coating aids having different properties.

It has now been found that compounds corresponding to the following general formula:

R(CH -(OCH CH OSO M wherein:

1111 stands for 0 in which case n is 1 or m stands for l to 30 in which case n is 0 to 1,

R stands for a branched-chain aliphatic group of 8 to 20 carbon atoms, which has at least 2 points of branching, preferably an aliphatic group of the formula Rz h wherein R stands for hydrogen or when n=1 may be alkyl such as methyl and each of R and R stands for a straight-chain or branched-chain alkyl group or together represent the atoms necessary to close an alicyclic ring structure, and

M stands for hydrogen, an alkali metal atom such as lithium, sodium, potassium, ammonium or organic ammonium, e.g. diethanol ammonium, triethanol ammonium, triethyl ammonium and morpholinium,

are excellent coating aids for use in coating compositions comprising a hydrophilic film-forming colloid such as gelatin. These coating aids are very easily to prepare and inexpensive.

Examples of coating aids of this nature are the sulphates derived from alicyclic alcohols such as hydroabietyl alcohol and from the widely known branchedchain primary oxo-alcohols having at least 10 carbon atoms and at least 2 points of branching such as isodecyl alcohol, isotridecyl alcohol, isohexadecyl alcohol and isooctadecyl alcohol. Isodecyl alcohol is a commercial material prepared from C -olefins (tripropylene) by means of the oxo-synthesis (cf. H. Rompp-Chemie Lexikon- Francksche Verlag, Stuttgart, West Germany) and is a mixture of primary branched-chain C -alcohols. Isotridecyl alcohol is a commercial material prepared from C olefins (triisobutylene, tetrapropylene or di(2-methyl-1- pentene)) by means of the oxo-reaction and is a mixture of primary branched-chain C -alcohols. Isohexadecyl alcohol and isooctadecyl alcohol are commercial materials prepared by aldol-condensation of C or C -aldehydes formed by oxo-synthesis; isohexadecyl alcohol is a mixture of branched-chain primary C -alcohols mainly consisting of alcohols as represented by the formula:

wherein R'=dimethylbutyl and R"=dimethylhexyl whereas isooctadecyl alcohol is a branched-chain alcohol for which the following formula is given:

CH| CH; CH: CH: H; C I CH1H-C H-CH:-CHs(il HCH|-+ CH;

OH; H: O H CH;

Other alcohols from which the branched-chain sulphates can be derived are the branched-chain alcohols having at least 2 points of branching prepared by alkaline condensation using catalytic amounts of alkali such as potassium hydroxide at temperatures comprised between 200 and 300 C. (known as Guerbet-reaction-see e.g. Fette-Seifen-Anstrichmittel, 71, No. 3, pages 215-218 (1969) of a branched-chain alcohol with the same or other branched-chain alcohol or with a straight-chain alcohol.

More details regarding the preparation, the composition and properties of branched-chain oxo-alcohols which can be usde to form the coating aids of the invention or which can be used to synthesize Guerbet alcohols for use in the preparation of coating aids of the invention can be found in Fortschr. Chem. Forsch. Bd. 11/1, pp. 121-134.

The following preparations illustrate how the coating aids of the invention can be prepared.

PREPARATION 1 Sodium isooctadecyl sulphate To a suspension of 28 :g. of sulphur trioxide in 200 ml. of anhydrous dichloroethane and 50 ml. of anhydrous dioxan a solution of 81 g. of isootadecyl alcohol (commercially available e.g. from Farbwerke Hoechst AG, Frankfurt (M), Hdchst, Germany) in 200 ml. of anhydrous dichloroethane was added dropwise at 5 C. The solution was kept overnight at room temperature. Subsequently, it was neutralized whilst stirring vigorously with a solution of 24 g. of sodium carbonate in 200 ml. of water. The mixture was concentrated till dry by evaporation at 50 C. in vacuum. The resulting solid product was dissolved in anhydrous ethanol and the sodium sulphate formed, was filtered off with suction. The ethanol solution was concentrated till dry by evaporation. Yield: 85 g.

PREPARATION 2 Sodium hydroabietyl sulphate of the formula:

ILC CHzO S O Na To a suspension of 29 g. of sulphur trioxide in 200 ml. of anhydrous dichloroethane and 60 ml. of anhydrous dioxan a solution of 105 g. of hydroabietyl alcohol in 500 m1. of anhydrous dichloroethane was added at 5 0., whereby a brown solution was obtained. The resulting solution was kept overnight at room temperature. Whilst stirring vigorously this solution was neutralized with a solution of 19 g. of sodium carbonate in 100 ml. of

water, whereupon the mixture was concentrated till dry by evaporation at 50 C. in vacuum. The solid product was dissolved in anhydrous ethanol and the sodium sulphate formed, was filtered off. The ethanol solution was concentrated by evaporation. Yield: 97 g.

PREPARATION 3 Sodium isohexadecyl sulphate To a suspension of 30 g. of sulphur trioxide in 300 ml.

of anhydrous dichloroethane and 60 ml. of anhydrous dioxan a solution of 77.5 g. of isohexadecyl alcohol (commercially available e.g. from Esso Belgium N.V., Antwerp, Belgium) in 300 ml. of anhydrous dichloroethane was added dropwise at 5 C. The resulting solution was kept overnight at room temperature. Whilst vigorously stirring the solution was then neutralized with a solution of 19.5 g. of sodium carbonate in 100 ml. of water, whereupon the mixture was concentrated till dry by evaporation at 50 C. in vacuum. The solid product was dissolved in anhydrous ethanol and the sodium sulphate formed, was filtered off. The ethanol solution was concentrated till dry by evaporation. Yield: 90 g.

PREPARATION 4 Lithium isohexadecyl sulphate This product was prepared in the same way as the compound of preparation 3, with the difference, however, that the reaction product was neutralized with lithium hydroxide. Yield: 87 g.

PREPARATION 5 Potassium isohexadecyl sulphate This product was prepared in the same way as the compound of preparation 3, with the difference, however, that the reaction product was neutralized with potassium carbonate. Yield: g.

PREPARATION 6 Triethylammonium isohexadecyl sulphate This product was prepared in the same way as the compound of preparation 3, with the difference, however, that the reaction product was neutralized with triethylamine. Yield: 75 g.

The compounds corresponding to the above general formula that comprise recurring ethylene oxide units can be prepared in a similar way from the corresponding ethoxylated alcohols e.g.

iS0-H C -(OcH CH 01-1 and 3a 1ez 2) 13 OH The coating aids according to the present invention promote the uniformity of coating and markedly reduce the tendency to form repellency spots. Coating compositions containing the coating aids of use according to the invention can be applied to dry surfaces as well as to wet surfaces and form layers that can be overco'ated easily in wet as well as in dry state, the said layers being either light-sensitive layers or not. Light-sensitive hydrophilic colloid materials comprising these coating aids also show improve wettability by photographic processing liquids.

It may sometimes be advisable to use blends of two or more coating aids according to the present invention. Indeed, it is observed frequently that one coating aid according to the invention performs best in one respect e.g. as regards its anticomet properties, whereas another is definitely superior in a different effect e.g. promoting uniformity of coating. These blends provide the major effects required and can often show characteristics superior to either coating aid alone. These effects may also result with blends of the coating aids of use according to the present invention with known coating aids such as saponine and other synthetic coating aids.

The coating aids of the present invention has also favorable properties for dispersing or emulsifying substances in hydrophilic colloid compositions, which as a result of the presence of said coating aids also show improved coating characteristics. For instance they are suitable as dispersing agent or emulsifying agent for substances that are to be incorporated into layers comprising a hydrophilic colloid and that would give rise to the formation of repellency spots in said layers when no compounds according to the invention were present.

Although the coating aids according to the present invention are mainly intended for use in coating compositions comprising gelatin as hydrophilic colloid, they can also be used as coating aid for coating compositions comprising other hydrophilic colloidal materials or mixtures of them, e.g. hydrophilic natural colloids, modified hydrophilic natural colloids or synthetic hydrophilic polymers. More particularly these colloids may be selected of such film-forming natural or modified natural hydrophilic colloids as e.g. glue, casein, zein, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, carboxymethyl hydroxyethyl cellulose, gum, arabic, sodium alginate and hydrophilic derivatives of such colloids. They may also be selected of such synthetic hydrophilic polymers as e.g. polyvinyl alcohol, poly-N-vinyl pyrrolidone, polyvinyl amine, polyethylene oxide, polystyrene sulphonic acid, polyacrylic acid, and hydrophilic copolymers and derivatives of such polymers. In this connection reference is made e.g. to UK. Patent Specification 1,139,891 filed J an. 5, 1965 by Gevaert-Agfa NV. and to French Patent Specification 1,507,874 filed Jan. 10, 1967 by Gevaert- Agfa N.V., which relate i.a. to heatand/or pressuresensitive materials comprising a recording layer mainly consisting of a dispersion of hydrophobic thermoplastic polymer particles in a hydrophilic colloid binder.

It has been found that coating aids according to the present invention improve the coating characteristics of coating compositions already at a concentration as low as 0.01% by weight relative to the weight of dry colloid. Larger concentrations, however, can also be used but generally the concentration is not higher than 5% by weight based on the weight of dry colloid.

The coating aids according to the invention are particularly suitable for use in a coating composition comprising gelatin as hydrophilic colloid, either as an aqueous solution of gelatin or as a photographic emulsion, which ordinarily is composed of an aqueous solution of gelatin containing as the light-sensitive material therein, a silver halide such as silver bromide, silver chloride, silver iodide. or mixtures thereof or another light-sensitive substance. The emulsion may contain other added substances such as sensitizing dyes, hardeners, stabilizers, pH-adjusting compounds, color couplers, antifogging agents, development accelerators, thickening agents, developing agents, softening agents, or the like. For instance, the coating aids of the invention are useful in gelatin photographic emulsions, not only those, which are non-optically sensitized, but also in orthochromatic and panchromatic emulsions. This also includes gelatin emulsions intended for color photography such as those containing color forming couplers and finegrain emulsions of the Lippmann-type.

The coating aids of use according to the present invention and their mixtures with other coating aids are also very useful in various other types of coating compositions in which gelatin is an important constituent, for example, in gelatin coating compositions to be applied as antihalation layer to the back or front of the base in a photographic material, as protective layer, as filter layer, as intermediate layer, as anticurling layer etc., which layers can also contain all kinds of other ingredients such as filling agents, hardening agents, antistatic agents, antifriction agents, or in any type of gelatin layer, which is coated from a composition comprising an aqueous solution of gelatin.

The coating compositions in accordance with our invention may be coated on a transparent support e.g. of glass, cellulose esters, polyethylene terephthalate, or on a non- EXAMPLE 1 A series of two aqueous gelatin solutions comprising per kg. 50 g. of gelatin were prepared.

To each of these gelatin compositions a certain amount of coating aid was added as listed in the table below.

After having been coated on a conventional subbed cellulose triacetate support the number of repellency spots in the layer formed was counted.

The results found are listed in the following table:

Coating aid used per kg.

gelatin solution: Repellency spots per sq. m. 15 ml. of a 12% aqueous solution of saponine (A) 24 (AH-10 ml. of a 5% aqueous solution of the compound of preparation 1 16 EXAMPLE 2 Example 1 is repeated with the difference that the coating aids listed in the following table were used:

Coating aid used per kg.

gelatin solution: Repellency spots per sq. m. (A) 16 (A)+10 ml. of a 5% aqueous solution of the compounds of preparation 2 6 EXAMPLE 3 Example 1 is repeated with the difference that the coating aids listed in the following table were used:

Coating aid used per kg.

gelatin solution: Repellency spots per sq. m. (A) 18 (AH-l0 ml. of a 5% aqueous solution of the compound of preparation 3 We claim:

1. A coating composition comprising a hydrophilic colloid and at least one surface active compound corresponding to the formula:

m stands for 0 in which case n is 1 or m: stands for 1 to 30 in which case n is 0 or 1,

M stands for hydrogen, an alkali metal atom, ammonium or organic ammonium, and

R stands for a branched-chain aliphatic group of 8 to 20 carbon atoms, which has at least 2 points of branching.

2. A coating composition according to claim 1 wherein tands for the group of the formula:

wherein R stands for hydrogen or when n=1 may be alkyl and each of R and R stands for a straight-chain or branched chain alkyl group or together represent the atoms necessary to close an alicyclic ring structure, the said group represented by R having at least two points of branching.

3. A coating composition according to claim 1, wherein the said compound(s) is (are) present in an amount of m stands for in which case n is 1 or m stands for 1 to 30 in which case n is 0 or 1,

M stands for hydrogen, an alkali metal atom, ammonium or organic ammonium, and

R stands for a branched-chain aliphatic group of 8 to 20 carbon atoms, which has at least 2 point of branchmg.

6. A photographic element according to claim 5, wherein in the said formula R stands for the group of the formula:

C- l R: R3 wherein R stands for hydrogen or when n=1 may be alkyl and each of R and R stands for a straight-chain or branched chain alkyl group or together represent the atoms necessary to close an alicyclic ring structure, the said group represented by R having at least two points of branching.

7. A photographic element according to claim 5, wherein the said compound is present in the said layer(s) in an amount of from 0.01 to 5% by weight based on the weight of dry colloid in the said layer(s).

8. A photographic element according to claim 7, wherein the said colloid is gelatin.

9. A photographic element according to claim 5, wherein said colloid layer comprising the said compound is a light-sensitive silver halide emulsion layer.

10. A photographic element according to claim 5, wherein the said colloid layer comprising the said compound is a protective hydrophilic colloid layer coated over a. silver halide emulsion layer.

11. The coating composition of claim 1 wherein the surface active compound is an isooctadecylsulfate.

12. The coating composition of claim 1 wherein the surface active compound is an isohexadecylsulfate.

13. A photographic element according to claim 5 wherein the compound of the designated formula is an isooctadecylsulfate.

14. A photographic element according to claim 5 wherein the compound of the designated formula is an isohexadecylsulfate.

References Cited FOREIGN PATENTS 747,801 4/1956 Great Britain 96-94 R I. TRAVIS BROWN, Primary Examiner A. T. SURO PICO, Assistant Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO- 850 Dated January 29, 1974 Inventor(s) Arthur Henri DE CAT ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, in the heading, line 6, in the inventors names, "Robert Joseph Pollet" should read Robert Joseph Pollet, Vremde Column 2,

line 18, "pervent" should read prevent Column 2, lines 20 21, "diffficult" should read difficult Column 3, Preparation 2, lines 56 65, the formula should appear as follows:

'Column 5, line 20, "gum, arabic, should read gum arabic, Column 5, line 47, "silver iodide. should read silver iodide, Column 6, Example 2, line 35, "compounds" should read compound Column 6, line 61, claim 2, before "stands" insert R Column 7, line 6, claim 5, "water-premeable" should read water-permeable Column 7, line 19, claim 5, "2 point" should read 2 points Signed and sealed this 22nd day of October 1974.

(SEAL) Attest:

McCOY M. GIBS ON JR. 0. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 6O376-P69 u.s. sovzmmzm- PRINTING OFFICE I969 0-366-584. 

